The present disclosure relates generally to systems and methods for recycling spent lead-acid batteries, and more specifically, relates to purifying and recycling the lead content of lead-acid batteries.
The lead used in the manufacture of the active material of new lead-acid batteries is typically in the form of lead oxide (PbO) that is typically produced by oxidizing a lead source having a high purity (e.g., 99.95% Pb). Lead oxide of high-purity is generally desirable when manufacturing lead-acid batteries since certain impurities (e.g., antimony, barium sulfate, tin) may enable side-reactions that can significantly affect battery cell performance. While it may be desirable to attempt to recover lead from the waste of spent or retired lead-acid batteries, this material may include a variety of lead compounds (lead alloys, oxides, sulfates and carbonates) and an array of physical and/or chemical impurities. Existing methods for purifying lead typically rely almost entirely on multi-stage pyrometallurgical smelting in which some these compounds are combusted to produce volatile gases, some of which must be scrubbed (e.g., captured and removed from the exhaust stream) to prevent release, in accordance with environmental regulations, and subsequently the remaining impurities are removed from the metallic lead in various refining operations. Since these operations often require specialized equipment and certain consumables (e.g., solutions or other refining agents), this refinement process generally adds cost and complexity to the lead recovery process.